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Physics and Astronomy Introductory Physics Labs

Physics Lab Notes and Reports

Contents

Documentation versus communication

Records of laboratory work take two forms. For documentation and reference purposes, the primary record of lab work is the lab notebook. This include the notes you make before, during, and after performing an experiment. For grading purposes, notebooks are not convenient. We ask that you record the observations you make in lab on green engineering paper. A small supply of engineering paper will be provided during your first lab. When you use up this supply, you are expected to purchase your own engineering paper.

For communication within a broader technical community, lab work is summarized in technical reports. These formal reports communicate your main results and omit many details recorded in your lab notebook.

We will require a unaltered set of lab notes, with a record of what you did for each lab. Because the preparation of proper lab reports require considerable time and effort, we will not require a complete lab report for each laboratory. For many labs, we will ask that you submit a well written, partial report, where you focus on particular communication tasks.

These two forms of communication employ different standards that can be only partially
implemented in an instructional lab. What we require is described below.

Lab notes1—official record of attendance and work performed

Lab notes consist of a series of dated entries, much like a personal diary. Although neatness is important, the content of your lab notes is the main criterion for grading. Lab notes should be sufficiently legible to make it easy for you and others to read and understand exactly what you did. To provide useful, verifiable documentation of your work, we require that:

  • Entries are handwritten with permanent black ball-point pen.
Notes that are not part of the permanent record can be made in pencil on scratch paper.
New entries are required after you change locations (e.g., start work at home).
  • Each entry must be signed and dated unambiguously.
For example: June 8, 2015, not 6/8/15.
  • Each entry needs a heading that clearly describes the work reported in the entry.
  • Errors must not be obscured or deleted.
Draw a single “X” or line through the incorrect material, make a short note in the margin explaining why it is wrong, then record the new, correct information in a new entry.
  • Your handwriting must be legible.
Numbers, symbols and units must be unambiguous. For example, sevens and twos must be clearly distinguished. Decimal fractions should be provided with leading zeros (0.12 kg, not .12 kg).
  • You must indicate whether you or your lab partner did each part of the work.
  • Your description of the work must complete. It must be understood without additional explanation.
  • You should “think in the notebook”. Ideas should be entered immediately and directly into the book, not transcribed later. When work must be transcribed, explain the circumstances.
  • Your original, in-lab work must be witnessed (signed) by your teaching assistant.
We require that your work be signed by your teaching assistant before you leave lab.
All your original notes must submitted in order to receive a grade.
Without your TA signature, your work for that particular lab will not be graded.

Unlike formal lab reports, lab notes do not have formal sections. While it is especially important to include procedures, each procedure is recorded as you actually perform it. You should indicate who performed which tasks. Use the first person to indicate when you did something. Use your lab partner’s name when your lab partner did it. Likewise you should record your data as you take the data. (There is no separate data section, but data tables can be helpful.) If you print a graph or data table in lab, staple it with your other notes as close as possible to the handwritten notes that describe the data and how it was collected. Do not collect your computer printouts at the end. Submitted your notes in chronological order.

Your lab notes must be sufficiently detailed that you or another student with your background can reproduce your work. The reader must be able to “trace” your work from the original data, through your analysis, to your conclusions. Your notes should leave no doubt about how the data were collected, what sensor settings were used (if any), or which equations were used to calculate the quantities you report. Define any symbols used in your equations and include appropriate units for numerical data. Unless you do the math by hand in your notes, a sample calculation should be provided for each set of calculations you perform in lab.

Special documentation requirements apply to graphs.Each graph printed during lab should fill a
full sheet of paper to allow room for notes. In some
cases it is useful to display computer-generated graphs, for example, showing position, velocity,
and acceleration as functions of time, on the same page to facilitate comparison between the
graphs. When it produces a larger graph, computer-generated graphs should be in the “landscape” (rather than “portrait”) mode.
Landscape mode will print the “x” axis along the longer dimension of the paper and thus makes
the graphs about 50% larger. All graphs must have a descriptive title that indicates what is being
graphed. (“Graph 1” or “Exercise 1” is not sufficient.) Labels and units are required for both the
x– and y-axes. If you are asked to draw a “curve” through your data points, this should always be
a best-fit curve (for example, a straight line if appropriate) that best represents your data. Best-fit
lines can be drawn by eyeball and a ruler, or with the help of the computer. If you’re asked to
calculate the slope (or perform other analysis) of the graph by hand, show the results of this
analysis directly on the graph, clearly identifying which graphical points were used to calculate
the desired quantities. When a computer-generated best fit curve is displayed on a graph, the
resulting equation (with parameters and uncertainties) should also be indicated on the graph. This
allows the reader to evaluate the curve fit results without referring back to the text. Refer to the
“Uncertainty/Graphical Analysis Supplement” (101/102 or 201/202 [205/206]) near the back of your lab manual for more
information about using graphs to find mathematical relationships between graphed quantities.

At the end of the semester, you will take a lab exam in which parts of a few selected experiments are to be reproduced—usually with small changes. You are expected to refer to your lab notes during the exam. The exam can be relatively easy if your notes are complete.

Keeping good records during lab takes time, and it is virtually impossible using formal English,
with complete sentences and paragraphs. Record your actions and data in the most clear, efficient
way possible. Use phrases instead of sentences. Annotated diagrams—simple sketches with the
parts labeled and notes—can save time and be more clear. Descriptive titles for graphs and table
columns are important. If an equation is used to describe the data in a graph, write the equation
on the graph. Putting it elsewhere usually requires additional text.

The first criteria for grading lab notes is completeness. With a copy of your lab notes, a student from another lab group should be able to set up the equipment, perform the experiment, and analyze the results without consulting the lab manual or other references. Your teaching assistant will deduct points for missing work that would be required to reproduce your results in lab. Points will also be deducted for poor or absent elements of documentation (illegible handwriting, undated entries, entries without headings, poorly labeled graphs, etc., as described above.) A few automatic grade deductions are described below in the “Special requirements for lab assignments” section.

Although you and your lab partner are expected to report the same data, text copied into your notes or report (for instance, from the lab manual, from your lab partner, or from the web) is prohibited. At the very least, no points will be awarded for copied work. Instances of repeated copying may result in a failing grade and will be referred to the Student Conduct Committee.

Lab notes are evaluated on the assumption that the reported data was acquired by you and your lab partner(s) during the current term in your assigned laboratory, and that each lab partner made a substantial contribution to the work. Reporting data collected by others (including your lab partner if you did not contribute to the work), or collected in previous semesters, is prohibited and may result in a failing grade.

Lab reports—formal communication with peers

Lab work is documented in lab notes and notebooks. Experimental results are communicated in technical reports. Unlike lab notes, these reports omit most “historical” aspects of the work: false starts are omitted. While one often reports the manufacturer and model number for important pieces of equipment, operational details are usually omitted. (The operational details must be recorded in your lab notes.) While lab notes often include derivations, technical reports normally include only the result. As communication devices, lab reports must conform to the standards of formal written English, with appropriate word choice, grammar, and structure.

Because writing formal lab reports is time consuming, an entire report will not be required for each lab. Instead, most labs will include a short writing assignment that focuses on one part of an entire report—perhaps an introduction or an experiment section. If the teaching assistant believes a submission is inadequate, the teaching assistant may require that it be rewritten and resubmitted for partial credit. As time permits, we will require complete, formal reports for one lab. The deadline for the submission of formal reports will be at least a week after the lab is performed. Your teaching assistant will inform you of the writing assignments on a week by week basis.

Lab reports (partial or complete) must be typewritten or printed from a text editor. The format employed for technical reports is specified by the recipient. The author has little discretion. In this course, we follow the style manual of the American Institute of Physics2 as described in the “Formal Lab Report Instructions” supplement near the back of the lab manual.

If you seek to improve your technical writing, useful references include the concise Strunk and White3 and any of several books on technical writing4. Washington State University’s Undergraduate Writing Center in Smith CUE 303 offers free, walk-in, peer-led tutoring that often helps with formal writing assignments. Most schools (including Washington State University) offer useful courses on technical writing at the junior level.

Formal reports will normally be evaluated on the basis of the following criteria:

  • Unity and Content. Format reports are organized around a conclusion. Your lab experiments are generally too broad for inclusion into a single, unified, report. You will be instructed to limit your report to a specific portion of the laboratory that will allow for one main conclusion. Everything in your report should be related in some way to this conclusion.
  • Coherence and Organization. Unlike lab notes, formal reports do have formal sections that depend on one another. You must clearly explain the logical connections between your experiment, your data, and your analysis, and how they support your conclusion.
  • Clarity. Ambiguities and statements that are “not even wrong” detract from your writing and will reduce your score. (Points will also be subtracted for factually incorrect statements.)
  • Conciseness. Points will be deducted for wordiness and unnecessary repetition.
  • Format. The format is specified in the Formal Lab Report Instructions” supplement to the lab manual. Points are normally be deducted for mistakes in word usage and spelling.

For grading purposes, we require that your complete, original lab notes must be submitted with the lab report. Failure to include the relevant lab notes will normally result in zero credit for the formal report. We expect that statements in your report (partial or complete) are supported by the data and analysis in your lab notes. Omissions and gaps in logic, when observed, will lower your grade.

If you intend to submit work from your physics lab with your Junior Writing Portfolio, it needs to be a formal lab report. Lab notes are not suitable for submission.

Special requirements for lab assignments

Cover Page

A cover page is required for every submission. It must include:

  • The title of the experiment
  • Your name and student ID number
  • The name of your lab partner
  • The date that the lab was performed
  • The name of your teaching assistant
  • The course and lab section numbers (for example, Physics 101, Lab Section 5)

Nothing else should appear on this page. Lab reports that are submitted in the wrong slot or are
otherwise misplaced take much longer to reach your teaching assistant if the information on the
cover page is incorrect or incomplete. Work submitted during lab may not require a cover page.
Please ask your teaching assistant if you are not sure.

Uncertainty analysis

Many experiments involve a quantitative comparison between values of the same quantity determined
by two or more distinct methods. When you compare two values, you must address the question of
whether or not they agree within the limits of the expected or measured uncertainties. Methods of
uncertainty analysis will be introduced as appropriate throughout the semester for Physics 101
and 201 students. As the semester progresses, you will need to make decisions by yourself on
appropriate methods for calculating the uncertainties in your various measured and calculated
quantities. Physics 102 and 202 students are expected to be aware of all the uncertainty methods
learned in Physics 101 and 201, respectively, and to use them appropriately. The Uncertainty/
Graphical Analysis Supplement (see: 101/102 or 201/202) near the back of your lab manual defines important quantities,
such as the standard deviation, and supplies details about determining uncertainties.

Automatic grade deductions

  • Late assignments are subject to a penalty of 10 points (out of 100) for every day the assignment is late. It is important to submit assignments on time, even if the work is incomplete. If you need an extension, contact the lab director before the due date.
  • Assignments placed in the wrong lab section slot in the large wooden cabinet located in the hall on the 3rd floor of the Webster Physical Sciences Building are subject to a 5 point deduction. For your convenience a list of all physics lab sections by course number, time of day, and name of the teaching assistant is posted on the cabinet.
  • Tutorial exercises submitted without your participation during the lab will receive at most 50% of the points possible for that assignment.

References

1. Howard M. Kanare, Writing the Laboratory Notebook (American Chemical Society, Washington, DC, 1985).

2. AIP Style Manual, Fourth Edition (American Institute of Physics, New York, 1990).

3. William Strunk, Jr., and E. B. White, The Elements of Style (MacMillan, New York, 1959, 1979).

4. For instance: Michael Alley, The Craft of Scientific Writing (Springer, New York, 1997).